Ultrasonic sector scanning search unit

ABSTRACT

A sector scanning search unit which supports a transducer for oscillation about a virtual pivot axis extending medially across the face of the transducer. The scanner unit is an elongate hand held unit in which the transducer is supported near one end of a chassis. The transducer&#39;s face is oriented transversely of a longitudinal axis of the chassis and on a side of the transducer opposite its supporting structure. The sector scanner is also provided with a mechanism for readily adjusting the magnitude of the sector being scanned, even while such scanning is taking place.

BACKGROUND OF THE INVENTION

1. Field of the Invention:

This invention relates to medical scanning apparatus and moreparticularly to a novel and improved ultrasonic scanning system usefulfor visualizing the condition of internal organs of a patient or thelike.

2. Description of the Prior Art:

Ultrasonic scanning of a test object in order to examine its interiorstructure is known in the art. Such ultrasonic scanning relies on theuse of a transducer which transmits ultrasonic energy into a subject andreceives reflections of that transmitted energy. These reflections arethen converted to electrical signals which typically are transmitted toa display apparatus where an image is produced on a cathode ray tubescreen.

In medical diagnosis it is now routine to position a transducer incontact with a patient for conducting a study. The transducer is thenrocked about an axis passing along the face of the transducer to scan asector. The most widely used apparatus and technique used for thispurpose is disclosed and claimed in U.S. Pat. No. 3,924,452 issued toMeyer and Wright on Dec. 9, 1975 and entitled "Sector ScanningUltrasonic Inspection Apparatus".

Cardiac studies are difficult with prior apparatus such as thatdisclosed in the referenced patent and other devices for two majorreasons. These reasons are:

1. The transducer should be pivoted quite rapidly to produce usefulimages. This requirement is due in large part to the rapid movement ofthe heart; and,

2. The transducer must be small and capable of accurate positioning atone of a few locations each between ribs of the patient.

Sector scanning devices have been proposed which are intended to be usedprimarily, if not exclusively, for cardiac studies. With these devicesthe rocking action of the transducer is achieved mechanically ratherthan manually as in the referenced patent. In some of these units themagnitude of sector scan is adjustable. When the sector scanning angleis relatively large a relatively broad area of the patient may besurveyed. When something of interest is noted the sector scanning anglemay be reduced to focus on the region of interest. Prior units haverequired that the scanning operation be temporarily stopped when it wasdesired to adjust the magnitude of the sector being surveyed.

SUMMARY OF THE INVENTION

A scanner unit incorporating features of this invention includes aframe, a transducer, and a transducersupporting structure projectingfrom the frame and mounting the transducer for oscillatory movementabout a virtual pivot axis. Drive means are also provided foroscillating the transducer support structure to effect the desiredoscillatory movement of the transducer. Means are also employed formechanically varying the magnitude of transducer oscillation while thatoscillation is occurring.

By being able to vary the magnitude of oscillation while thatoscillation is occurring the operator of the scanner unit can scan abroad sector and then narrow down his field of search without losing hisplace or wasting time. This offers a clear advantage over prior artmechanisms which did not allow variation of the sector scan angle duringoscillation.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view of a sector scanning search unit incorporatingfeatures of this invention and shown connected in an ultrasonic testingsystem.

FIG. 2 is a view similar to FIG. 1, with parts removed, to reveal thearrangement of components on the unit chassis;

FIG. 3 is an elevation view of the unit illustrated in FIG. 2;

FIG. 4 is a perspective view of the power train employed in the unit ofFIG. 1;

FIG. 5 is an exploded view of the variable oscillation mechanism shownin FIGS. 2 and 3;

FIG. 6 is an exploded view of the transducer supporting structure shownin FIGS. 2 and 3; and FIG. 7 is a simplified elevation view of thetransducer supporting structure illustrating the relative orientationsof the pivot axes of the linkage comprising the structure.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to FIG. 1, a hand-held ultrasonic scanner unit 10 isillustrated which incorporates features of this invention. The unit 10is shown connected to an ultrasonic medical diagnosis unit 12 by anelectric signal/power cable 14.

The scanner unit itself includes an elongate, casing 18 which can behand carried and manipulated. The casing 18 encases an elongatecomponent supporting frame or chassis 20.

Referring to FIGS. 2 and 3, the unit 10 is illustrated with the casing18 removed so that the overall arrangement of components on the chassiscan be viewed. The chassis 20 supports a power train, generallyindicated at 30 and shown more clearly in FIG. 4, a variable oscillationmechanism, indicated generally at 100 and shown in more detailed in FIG.5, a driving link 200, more clearly shown in both FIGS. 5 and 6, atransducer supporting structure, indicated generally at 300 and shownmore clearly in FIG. 6, and a transducer 400, also clearly shown in FIG.6.

Power in the form of rotary motion is generated in the power train 30and transmitted to the variable oscillation mechanism 100 which convertsthat rotary motion into an oscillatory motion. The driving link 200connects the variable oscillation mechanism 100 and the transducersupporting structure 300. Any oscillating motion produced at thevariable oscillation mechanism is transmitted to the driving link 200.The driving link, in turn, conveys to the support structure 300 thetranslational component of the oscillatory motion which is coaxial withthe axis of the link 200. The translational magnitude of the componentof the oscillatory motion can be varied at any time, even whileoscillatory motion is being produced, merely by manually adjusting theoscillation mechanism. Translational motion of the driving link 200 isconverted back to oscillatory motion by the support structure 300. Thestructure 300 supports the transducer 400 for oscillatory movement abouta virtual pivot axis 410 extending across the face of the transducer.Consequently any translational movement of the driving line 200 ismanifested as an oscillation of the transducer 400.

The power train 30 comprises a motor 31 which includes a drive shaft 32extending axially of both the motor 31 and the chassis 20. The driveshaft 32 extends through a chassis wall portion 20a and supports adriving pinion 34 for rotation on the opposite side of the wall portion20a from the motor 31. The driving pinion 34 is a bevel gear whichmeshes with and drives another bevel gear 36 supported at right anglesto the driving pinion 34. The driven gear 36 is fixedly mounted to adrive shaft 38. The drive shaft 38 is rotatably supported at one end ina bearing 40 disposed in a chassis wall portion 20b. At its opposite endthe drive shaft 38 supports an enlarged cylindrical head 50 whichsupports an offset or eccentric cam 52 (See FIG. 4).

The power train 30 produces a rotary output which must be converted intooscillatory motion to effect the desired oscillation of the transducer.The variable oscillation mechanism 100 is therefore disposed incommunication with the output end of the power train 30.

Referring to FIG. 5, the output end of the power train 30, comprisingthe rotating eccentrically mounted cam 52, is shown in relation to thevariable oscillation mechanism 100. The oscillation mechanism 100includes separate subassemblies for converting the power train's rotarymotion to oscillatory motion and for adjusting the magnitude of theoscillatory motion which is eventually transmitted to the transducersupport mechanism 300.

The oscillation producing subassembly comprises a U-shaped slider member110 which is, at the same time, confined to move linearly across a faceof a hub 120 and to engage the rotating cam 52.

The hub 120 supports the output end of the power train 30 and is a guidefor the slider member 110. The hub 120 is rotatably mounted to thechassis 20 coaxially of the drive shaft 38. A reduced diameter section120a of the hub 120 is disposed within a mating circular passage 22 in achassis wall portion 20c. A bore 121 extends axially through the hub 120from one of its opposed faces 122 and terminates centrally of anenlarged recess 123 disposed in the hub's opposite face 124. A bearing125, disposed within the bore 121, rotatably receives the output end ofthe coaxially aligned drive shaft 38. The recess 123 is dimensioned toreceive the enlarged cylindrical head 50 on the output end of the driveshaft 38. The hub face 124 supports a pair of diametrically opposed pins128 which extend axially from the face 124. The pins 128 each support abearing 130.

The U-shaped slider member 110 is a cam follower for the cam 52. Thatslider member comprises a U-shaped center section 112 and a pair ofoppositely entending wing portions 114. The member 110 is sidablymounted to the hub's face 124 so the recess 115, defined by the U-shapedcenter section, faces the recess 123 and mates with the cam 52. Thewings 114 include aligned elongate slots 116 which each engage one ofthe bearings 130. As the cam 52 rotates within the recess 115 to slidermember 110 oscillates back and forth across the hub face 124 is guidedby the bearings 130 each.

A slider retainer 140 is employed to retain the slider 110 adjacent theface 124 of the hub 120 so that the slots 116 in the slider aremaintained in engagement with the bearings 130 in the face of the hub.The retainer 140 is a torus shaped member which is attached to the hubface 124 with a pair of fasteners 142.

In order to transmit oscillatory motion of the slider 110 to the drivinglink 200, a low friction connection is provided between thesecomponents. A pin 150 is mounted to the slider center section 112 andextends outwardly through the center of the retainer 140. A bearing 152,mounted to the pin 150, mates with a loop like end portion 210 of thedriving link 200. any oscillatory motion which is imparted to the slidermember 110 is conveyed by this low friction connection to the drivinglink 200. A retainer 220 is employed to maintain the end portion 210 ofthe driving link in mating engagement with the bearing 152. Thatretainer 220 is attached to the retainer 140 by a pair of fasteners 222.

Generally speaking, oscillatory movement of the driving link 200 isproduced by operating the power train 30 so that the eccentric cam 52rotates in the recess 115 of the slider 110 which responds to such camrotation by oscillating past the guide bearings 130 and over the recess123. Any oscillatory movement of the slider 110 is transmitted directlyto the driving link 200.

It is desirable to be able to control the amount of oscillatory motionwhich the driving link 200 imparts to the transducer support structure300. The variable oscillation mechanism 100 achieves that control bymeans of an oscillation adjusting subassembly 160 which can control thecomponent of oscillatory motion of the slider 110 in the direction ofthe longitudinal axis of the driving link 200.

The oscillation adjustment subassembly operates by selectively rotatingthe slider 110 with respect to the link 200. When the axis of theoscillatory motion of the slider 110 approaches or coincides with thelongitudinal axis of the link 200, the component of oscillatory motiontransmitted through the driving link 200 to the transducer supportstructure 300 will be at a maximum value. When the axis of oscillatorymotion of the slider 110 is approaching a right angle with respect tothe longitudinal axis of the driving link 200, the component ofoscillatory motion transmitted through the link 200 to the transducersupport structure 300 will be at a minimum valve.

The oscillation adjustment subassembly, indicated generally at 160(Shown in FIG. 5), enables the hub 120 to be rotated a desired amountwith respect to the chassis 20 so the slider 110, mounted to the hub,rotates with respect to the driving link 200.

The subassembly 160 comprises a plate 162 which is secured for rotationwith the hub 120 by means of a pair of fasteners 163. The plate isdisposed coaxially with the drive shaft 38 between the chassis wallportion 20c and the driven gear 36. An opening 164 disposed centrally inthe plate, enables the drive shaft 38 to extend through the plate 162and to rotate freely without interference. A washer 165 is interposedbetween the plate 162 and the chassis wall portion 20c to reduce anysliding friction which would otherwise be encountered if the plate 162were to rub directly against the wall portion 20c. The plate 162 alsoincludes a projection 166 which extends radially outward from theperiphery of the circular plate 162.

The subassembly 160 also comprises a slider 170. The slider 170 includesan outwardly extending projection 172 and a pair of elongate guide slots174, only one of which is shown. Referring to FIG. 2, it is seen that anelongate switch bracket 60 is attached to the chassis 20. The bracket 60supports the slider 170 for longitudinal movement along the longitudinalaxis of the chassis. The switch bracket 60 includes an elongate centralrecess 62 which defines a path for the slider 170. The opposed elongateside edges of the recess 62 are engaged by the slider's guide recesses174. A slot 176 is disposed in the slider 170 so that an actuator 177(See FIG. 1) mounted externally of the casing can mechanically engagethe slider. The plate 162 and the slider 170 are interconnected by alink 178 which pivotally engages the projections 166, 172 on the plateand slider, respectively.

Operation of the oscillation adjustment subassembly to effect rotationof the hub 120 and the attached slider 110 is initiated bylongitudinally moving the slider 170 in the switch bracket recess 62.The link 178 transmits this motion to the plate 162 which is then causedto rotate. Since the hub 120 and the plate 162 are directly connected tohub 120 will undergo a similar rotation, reorienting the slider 110accordingly.

An on-off switch 180 is disposed at one end of the travel of the slider170. The on-off switch 180 connects the power cable 14 and the motor 30.When the slider 170 is positioned at the end of its travel, as shown inFIG. 2, the switch 180 is opened and no current passes to the motor.When the slider moves from that end position, the motor 120 isactivated. Defined "on" positions may be provided wherein the hub 120and slider 110 are rotated to particular orientations and the transducerconsequently oscillates over specific sector angles.

In order to locate the hub 120 in a particular orientation, a detentmechanism 190 (see FIGS. 2 and 3) is provided which is mounted to thechassis 20. A plurality of notches, only one of which is shown at 191,are provided at particular points along the periphery. Each notch isrelated to a particular magnitude of sector scan for the transducer. Forexample, notches may be provided to produce transducer sector scans of20°, 30°, 45°, and 60° respectively. Indicia may be put on the casing(See FIG. 1) to indicate these positions. Interengagement of the detentmechanism 190 with one of the notches 191 locates the hub 120 and slider110 in a particular orientation.

The detent mechanism 190 is shown in detail in FIGS. 2 and 3. A detentarm 192 is provided which is pivotally mounted at one end of the chassis20 and positioned so that it is located adjacent the periphery of thehub 120. The detent arm 192 carries a bearing 194 which is adapted toengage a selected one of the notches in the hub periphery in order tolocate the hub. A spring 196 interconnects the opposed end of the detentarm 192 to the switch bracket 60. The spring 196 resiliently biases thedetent arm 192 toward the hub 120 so the bearing 194 is urged intorunning engagement with the periphery of the hub 120. Consequently, thebearing 194 will be resiliently urged into whichever hub periphery notchpasses under the bearing as the hub 120 is rotated by manipulation ofthe actuator 177. Advantageously, while the motor is on and oscillatorymotion is being generated and transmitted to the transducer supportstructure 300, the subassembly 160 enables the hub to be simultaneouslyrotated so the magnitude of the oscillatory motion being so transmittedcan be varied.

The transducer structure 300, the which oscillatory motion istransmitted by the driving link 200 comprises a pantographic framestructure which is supported in centilevered fashion from one end of thechassis 20. That transducer supporting structure supports the transducer400 for oscillatory movement about a virtual pivot axis 410 whichextends medically across the transducer face. Basically, thepantographic frame comprises six pivotally interconnected links 320,360, 380, 382, 391, 392 arranged in parallelogram fashion for movementwith respect to each other when motion is applied to one of the links.the pantographic frame linkage is shown in detail in FIG. 6 andschematically in FIG. 7.

A first link 320 comprises a split hub bell crank which is intended tobe mounted to a potentiometer 332. Portions 20d and 20e of the chassis20 include apertures 324, 326 which are coaxially aligned with an axis322. The apertures 324, 326 each receive similar coaxially alignedbearings 328, 330. The potentiometer 332, clamped to the chassis by abracket 338, has a shaft 334 which is disposed coaxially with the axis322 and supported in the bearings 328 and 330. The split hub bell crankis disposed between the chassis portions 20d and 20e. An aperture 336 inthe bell crank 320 is positioned coaxially with the axis 322 and thebell crank 322 is clamped to the potentiometer shaft 334 by a clampingscrew 335 (See FIG. 2). The first link 320 also includes an aperture 340offset from the aperture 336. The aperture 340 supports a bearing 342which receives a pin 230 extending from one end 232 of the driving link200.

A second link 360 comprises a transducer supporting link for receivingand removably supporting the transducer 400. The second link lies inopposed relation to and parallel with the first link 320.

An intermediate pair of links 380, 382 interconnect the first and secondlinks 320, 360, to close the parallelogram. The link 380 is connected tothe first link 320 at pin 384. The link 380 is connected to the secondlink at pin 386. The link 382 is connected to the first link 320 at thepin 388. The link 382 is connected to the second link 360 at pin 390.Note that the intermediate links 380, 382 are each chosen to have adistored H-shape for increased rigidity of the pantographic linkage.Such an H-shaped structure permits the second link 360 to be pinned afour points. It also facilitates the use of two intermediates cranks,discussed hereinafter.

An intermediate crank structure comprises a pair of cranks 391, 392which are mounted intermediate their ends to a shaft 393 supported by achassis portion 20g. The intermediate crank members 391, 392 includepins 394, 395 and 396, 397, respectively, at their opposed ends, whichpins engage the respective intermediate links 380, 382 at points betweenthe ends of those intermediate links.

The relative orientation of the pivot points in the transducersupporting structure 300 facilitates oscillation of the transducer 400about the virtual pivot axis 410 which extends across the face of thetransducer 400 medially of the extremities of the transducer face. Whenthat transducer face is circular, the virtual pivot axis 410 coincideswith a line running diametrically through the center of the face.

Referring to the schematic illustration of the structure 300 in FIG. 7,it is noted that points on the pivot axes of the transducer supportinglink 360 form the vertices of a triangle ABC. Note that the point Cindicates the virtual pivot axis 410 extending across the face of thetransducer. Similarly, points on the pivot axes of the intermediatelinks 391, 392 form the vertices of a triangle A' B' C'. Finally, it isnoted that the points on the pivot axes of the bell crank 320 form thevertices of a triangle A" B" C". Note that both point C' and C" indicatefixed pivot axes through shafts about which the intermediate cranks 391,392 and the bellcrank 320, respectively rotate. All three of thesetriangles are congruent and remain congruent, irrespective of theorientation of the respective links of the support structure 300.

Other geometric relationships of the pivot axes of the transducersupport structure 300 are also worthy of note. The pivot axes throughthe points, C, C', and C" always lie parallel to each other and in acommon plane. Also, the pivot axes through the points A, A', and A" arealways parallel and coplanar. The same holds true for the pivot axesthrough the points, B, B', and B". Finally, a plane through the pivotaxes containing the points A, A' and A" is parallel to a plane throughthe pivot axes containing the points B, B', and B".

When a transducer supporting structure 300 incorporates these geometricrelationships and when such a structure is pinned to a chassis at C",C', the result is that any oscillation imparted to the first link 320will be transmitted without distortion to the second link 360. Thoughthe link 360 is not pinned at its pivot point C, that pivot point bearsthe same relation to the pivot points A, B as the pivot point C" bearsto the pivot points A", B". In other words, though on physical structurecoincides with the axis 410, that axis is fixed. The link 360 can bestructured to support the transducer 400 so that the transducer facelies on this fixed virtual pivot axis 410 through point C and so thataxis 410 passes medially of the extreme ends of the surface 410. Given aconventional circular transducer surface, the surface can be oriented sohalf of that surface will lie above the axis 410 and half of thatsurface will lie below the axis 410. When any oscillatory motion isimparted to the link 360 supporting such a transducer, there will be aminimum amount of transducer wiping movement about the transducer'spivot axes. Consequently, there will be a minimum amount of irritationon the skin of the patient being examined.

In the operation of this unit, movement of the actuator 177 from the"off" position to one of the "on" positions (e.g., 20°, 30°, 45°, or60°) permits the switch 180 to close, thus conducting electric powerfrom the cable 14 to the power train 30 at the motor 31. When the motor31 starts operating, the gear 34 rotates and effects rotation of themating gear 36 and the drive shaft 38 mounting gear 36. Theeccentrically mounted cam 52 rotates with the drive shaft 38 and effectstranslational oscillation of the slider member 110. That oscillatorymotion is transferred to the driving link 200 connected the slidermember 110.

The actuator 177 is connected to the slider member 110 by theoscillation adjustment subassembly 160. Movement of the actuator 177effects rotation of the slider into any one of a number of distinctpositions in which the orientation of the slider member 110 is variedwith respect to the driving link 200 so that the component ofoscillatory motion which extends along the axis of the link 200 isvaried.

The link 200 is connected to the first link or bell crank 320.Oscillatory motion transmitted to the link 320 by the link 200 istransmitted to the second or transducer supporting link 360. Theorientation of the elements and pivot axes of the supporting structure300 is such that rotation of the first link 320 about the axis of thepotentiometer shaft 334 produces corresponding rotation of thetransducer support link 360 and its transducer 400 about the fixedvirtual pivot axis 410. With this arrangement there is no physicalstructure located in close proximity to the transducer surface which mayinterfere with positioning of the transducer against the patients body.Yet, the axis 410 is located on and centrally of the transducer face sothat the transducer is enabled to oscillate about that fixed axis andminimize wiping action against the body of the patient.

The adjustable oscillation subassembly 160 enables the magnitude oftransducer oscillations to be varied even while the search unit isscanning so the operator can easily move from a broad sector scan to anarrower one without losing his location or wasting time.

Another advantage of this structure is that it is easily manipulable toexamine a patient. Its elongate chassis facilitates manipulation. Theoscillating transducer being supported axially outward and endwise ofthe chassis and the transducer face oriented transverse to thelongitudinal axis of the chassis means that the chassis itself will notinterfere with the body of a patient being examined. Consequently, mostany area of the body can be subjected to examination by the oscillatingtransducer of this apparatus.

Although the invention has been described with a certain degree ofparticularity, it is understood that the present disclosure of thepreferred embodiment has been made only by way of example and thatnumerous changes in the details of construction and the combination andarrangement of parts may be resorted to without departing from thespirit and the scope of the invention as hereinafter claimed.

What is claimed is:
 1. An ultrasonic scanner unit, comprising:(a) aframe; (b) a transducer; (c) transducer support structure projectingfrom said frame and mounting said transducer for oscillatory movementabout an axis; (d) drive means for driving said transducer supportstructure to effect oscillatory movement of said transducer about saidaxis; and (e) oscillation varying means operatively interposed betweensaid transducer support structure and said drive means for mechanicallyvarying the magnitude of transducer oscillation while said drive meansis driving said transducer support structure.
 2. The ultrasonic scanningunit of claim 1 where the oscillation varying means comprises anadjustable control element which controls the extent of oscillation ofsaid transducer, said element movable to a position for fixing thetransducer relative to the frame.
 3. An ultrasonic scanner unit,comprising:(a) a frame; (b) a transducer; (c) a transducer supportstructure projecting from said frame and mounting said transducer foroscillatory movement about a virtual pivot axis; (d) drive means foroscillating said transducer support structure to effect oscillatorymovement of said transducer about said virtual pivot axis; (e) saiddrive means comprising:(i) a source of power mounted to said frame; and(ii) an oscillatory driving link connected to said transducer supportstructure; and, (f) means for mechanically varying the magnitude ofoscillation while the oscillation is occurring, said oscillation varyingmeans interconnecting said source of power and said oscillatory drivinglink for variably controlling the amount of oscillation imparted to saiddriving link.
 4. The ultrasonic scanning unit of claim 3 where the meansfor mechanically varying the magnitude of oscillation comprises anadjustable control element for varying the extent of oscillation of saidtransducer, said element movable to a position for fixing the transducerrelative to the frame.
 5. The scanner unit of claim 4 wherein saidsource of power terminates in a rotatable, shaft mounted eccentric andwherein further said oscillation varying means includes a connectingmember which coacts with both said eccentric and said driving link, saidconnecting member oscillating over a fixed distance in response torotation of said eccentric, the orientation of said connecting memberwith respect to said driving link being variable to vary the componentof oscillatory movement of said connecting member which is transmittedto said driving link.
 6. The scanner unit of claim 5 wherein saidconnecting member comprises a slider which is assembled to one face of arotatable hub, said hub face including a recess for receiving saidrotatable eccentric, said slider including a slot communicating withsaid recess, said eccentric mating with said slot for impartingtranslational sliding motion to said slider across said hub face, saidhub slider assembly being rotatable through a range of positions tovariously orient the axis of translational movement of said slider withrespect to the axis of oscillatory movement of said driving link.